Contrast agents for use in diagnostic computed tomography imaging

A composition useful for conducting computed tomography comprising a compound of general formula (I) in the form of a complex with Gd3+ and/or in the form of a metal complex with a metal ion suitable for computed tomography,

• in which
• Ar represents a group selected from
• wherein # indicates the point of attachment to X,
• X represents a group selected from
• CH2, (CH2)2, (CH2)3, (CH2)4 and *—(CH2)2—O—CH2—#,
• wherein * indicates the point of attachment to Ar and # indicates the point of attachment to the acetic acid moiety,
• R1, R2 and R3 represent, independently for each occurrence, a hydrogen atom or a group selected from C1-C3-alkyl, —CH2OH, —(CH2)2OH and —CH2OCH3,
• R4 represents a group selected from C2-C5-alkoxy, (C1-C3-alkoxy)-(CH2)2—O—, (C1-C3-alkoxy)-(CH2)2—O—(CH2)2—O— and (C1-C3-alkoxy)-(CH2)2—O—(CH2)2—O—(CH2)2—O—,
• wherein said C1-C3-alkoxy groups and C2-C5-alkoxy groups are optionally substituted, one, two, three or four times, with a fluorine atom,
• R5 represents a hydrogen atom or a group selected from C2-C5-alkoxy, (C1-C3-alkoxy)-(CH2)2—O—, (C1-C3-alkoxy)-(CH2)2—O—(CH2)2—O— and (C1-C3-alkoxy)-(CH2)2—O—(CH2)2—O—(CH2)2—O—,
• and
• R6 represents a hydrogen atom or a group selected from C2-C5-alkoxy, (C1-C3-alkoxy)-(CH2)2—O—, (C1-C3-alkoxy)-(CH2)2—O—(CH2)2—O— and (C1-C3-alkoxy)-(CH2)2—O—(CH2)2—O—(CH2)2—O—,
• or a stereoisomer, a tautomer, an N-oxide, a hydrate, a solvate, or a salt thereof, or a mixture of same for computed tomography imaging, preferably of the vascular, renal or of the hepatobiliary system or of the gastrointestinal tract, more preferably for computed tomography imaging of the liver.